Method of heating and cracking oil



May 24, 1932. J. c. BLACK ET AL METHOD OF HEATING AND CRACKING OIL Filed Nov. 16, 1926 ture in ordinary furnace construction.

Patented May 24, 1932 UNITED STATES PATENT OFFICE JOHN C. BLACK, OF DESTREHAN, LOUISIANA, AND EAR/LE W. GARLD, OF LONG BEACH, CALIFORNIA METHOD OF HEATING AND CRACKING GIL Application filed November 16, 1926. Serial No. 148,735.

This invention pertains to a method and apparatus for cracking oil, especially for cracking oil in liquid phase, and pertains to such a process as is described in Patent #1356419. It is more particularly directed to a process of cracking oil where an oil is raised to the cracking temperature and then maintained at substantially said cracking temperature, or at a higher temperature for a prolonged period of time while maintained under a pressure suificient to prevent any substantial vaporization. It is an object of this invention to devise a method and apparatus by which the oil may be maintained at this cracking temperature, or at a higher temperature, for any predetermined length of time to obtain any desired amount of cracking.

We have found that it is particularly diificult to maintain an oil at any given temperIa- 11 passing oil through coils heated by combustion gases there is a tendency for the oil to fluctuate in temperature during its passage through the tubes due to radiation and in equalities in the heating. Another danger in heating the oil at the cracking temperature is overheating, with consequent carbonization and gasification. It is therefore an object of our invention to devise a method and apparatus for heating oil wherein the oil may be raised to cracking temperature and maintained at substantially said cracking temperature during passage through the coils in a furnace, wherein the tendency for superheating the oil is minimized or completely eliminated, and the temperature of the oil maintained substantially constant during its passage through the coils. Another object of our invention is to devise an apparatus for cracking oil wherein the heat economy and heat distribution is at a maximum, and in which the capacity, that is, the volume of oil which may be treated for any given furnace volume, is at a maximum. Another object of our invention is to devise an apparatus wherein repairs or replacement of tubes is made easy, and is facilitated. Further objects of our invention will appear from the following description and particularly by reference to the accompanying drawings which illustrates our invention. 7

In said drawings Figure 1 is a sectional view of an elevation of the front end of a furnace. Figure 2 is a side elevation of one of the vertical banks of the furnace. Figure 3 is a plan view of said vertical bank. Figure 4 is a right side view of Figure 2, and Figure 5 is a left side view of Figure 2.

In Figure 1', 1 is a setting of the furnace. 2 is the firewall separating the furnace into two sections, creating in fact two separate furnaces. 3 are the arches for the furnace. L is the fire-box of a Dutch oven, and 5 is the Dutch oven arch. 6 is the front wall of the furnace. On said wall is an H beam, 7 supported on plates 8 in the side wall of the setting. On this H beam is set a removable I beam 9. Supported on said I beam 9 are a plurality of removable channels 10 and 11. These channels are pierced withholes through which the tubes 12 pass loosely so that the tubes 12 may be easily removed and also to allow the gases of combustion to circulate around the ends of the tubes and the crossovers, thus keeping them at substantially the same temperature as the tubes actually in side the furnace. The channel 10 contains one single row of tubes cross-connected between the furnaces as shown. The channels 11 each contain two rows of tubes which are connected to analogous rows in the other furnaces shown. The course of the oil through these tubes is as shown, first, into the bottom row or pass of the left-hand furnace across to the bottom row or pass of the right-hand furnace, up to the row immediately above in the right-hand furnace; across to the row immediately above in the left-hand furnace, and up through the next three rows in analogous manner as indicated.

The tubes are all welded together. On cutting the cross-connections from one channel section to the channel section immediately above and the cross connection between furnaces, each channel section may be separately removed. This removal is facilitated by the I beam space 9. Thus by supporting the channels 10 and 11 by means of a sling caught around the tubes 12 in said section, and

around the tubes in section 15 or around some outside support, the beam 9 may be removed. The channel 10 may then be dropped and removed without interference from the tubes 12 in channel 11 which are usually sagged because of the heat in the furnace.

13 is an H beam set in the setting of the furnace and supported on plate 14. On this H beam are set a plurality of vertical banks of coils 15. Each of these sections is composed of a sinusoidal header as shown in Figures 1, 4, and 5. The header 16 isa cast I beam section as shown in Figure 3. This header is pierced by a plurality of staggered holes through which tubes 17 pass. The course of the oil in tubes through each header is such as to move upward zigzag across the header, across the top of the header and down zigzag on the other side of the header as shown. There is a slight space between the headers as indicated on Figure 1 so that each header may be easily removed.

The course-of the oil from the lower coils is as shown on Figure 1, upward through the right-hand pass of the coils in the bank, across and downward through the left-hand pass of the bank, across to the next vertical pass in the adjoining bank, upward through the right-hand pass, downward through the left-hand pass in an analogous manner upward and downward through the adjoining tubes welded into the tubes so as to provide this dead-end. The purpose of said deadend isto allow the use of a block for cleaning out the individual tubes.

The operation of t'hefuniace is as follows:

I The oil is introduced into the lower banks of coil in channel 10, and is raised during its passage through the tubes 12 in channels 10 and 11 so that it reaches the cracking point at the exit from the upper horizontal pass.

' The course of the oil is concurrent with the The purpose of combustion gases as shown. the concurrent passage is to prevent the oil,

as it reaches t'l 1e cracking temperature, which has received an incipient cracking, from coming in contact with the hot combustion gases entering the furnace from Dutch oven. Were this allowed, these hot gases might cause a superheating of the oil with consequent carbonization and gasification. By

passing the oil concurrently with the combustion gases, as the oil is heated up and partially cracked, it is removed from the region of hot combustion gases to a region of cooler combustion gases.

The oil is then passed to the reaction coils 17 where the oil is maintained at the cracking temperature. It will be seen that by passing the oil concurrently with the combustion gases, and by placing the oil at or near its cracking temperature in the proximity of the reaction coils, any cooling down of the reaction coils is prevented. This cooling would be obtained were the cold oil passed in through the upper horizontal coils and passed counter-current with combustion gases. This cool oil would tend to cool down the reaction coils and cause a fluctuation in the temperature of the oil passing through the reaction coils 17.

By passing the oil from one horizontal coil in one furnace tothe analogous horizontal coil in'the other'furnace, and back and forth in this manner as shown, an equalization in the load on both furnaces is obtained and their simultaneous control is therefore facilitated. This would be equivalent to a single furnace of double the width. By spreading the coils in width, the'vertical height of the coil is diminished and the concentration of the fire diminished so reducing the blasting effect ofthe flames.

The oil, as shown, passes up from the prcheating coils 12 to the creeling coils. The oil comes in into the lower coils in the lefthand furnace, leaves the preheating coils in the right-hand furnace, enters the reaction coils inthe right-hand furnace an d leaves the reaction coils in the left-hand furnace, that is, in thesanie furnace as that to which the cold oil enters. major'amount of heating occurs in the lowest bank of coils, that is, in the coils in channel 10 in the left-hand furnace. The major amount of cracking occurs in coil 17 in the right-hand furnace, and the minor amount ofcracking occurs in the coils in the left-ha ml furnace. There'is, therefore, an equalization of load on each furnace.

The lowest bank of coils in the furnaces receive the major amount of heating, and there fore are the easiest burnt out. hey are, placed in single pass so that their removal facilitated, as described above. By staggering the tubes in the furnace the channeling of the gases is prevented and a complete onvelopment of the tubes and distribution of the gases throughout the furnace is made possible.

Another advantage of the staggering is that it permits the replacement of worn tubes by new tubes. The tubes, because of the heat, are caused to sag considerably, and this saggingis so marked that if any tube in any of the intermediate banks was removed and a new tube introduced, the introduction of this As will be apparent, the

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tube would be interfered with by the sagging of the upper tubes. By staggering the tubes as shown, a new straight tube may be introduced without interference by the sagging of the upper tubes, since the distance between the center of the tubes is greater than that which would be obtained by placing the tubes in the same planes, or immediately over each other.

The sinusoidal form of the headers 16 permits of the placing of a greater number of tubes in the same volume of furnace space. The unit construction of the banks permits of the same ease of replacement of tubes as that obtained in the unit construction of the lower tubes, for if one tube should need repairing the whole bank may be removed easily and a new bank slipped into place immediately and the tubes replaced or repaired when convenient without interrupting the operation of the furnace for an undue length of time. Another advantage of the use of vertical banks is that the removal of one bank is is not interfered with by the sagging of the tubes, as is the case, were the units placed horizontal as in the case of the coils 12.

The construction of the reaction coil or cracking coil 17 permits of the equalization of temperature throughout the coil, and therefore enables the oil to be maintained at a substantially constant temperature throughout its passage through the coils. By passing the oil upward in single passes from the hottest to the coldest zone of the furnace, any accidental over heating of the oils .is

minimized by tl e fact that it is immediately removed from the hotter zone to the cooler zone. By immediately returning the oil from this single upward pass downward through another single pass to the hotter zone of the furnace, any accidental cooling of the oil below the desired cracking temperature is immediately neutralized by the fact that it passes into the hotter zone of the furnace. Each down pass as will be seen, is between two upward passes so that there is an equalization of temperature between the up and the down passes, aiding in the maintainment of a constant temperature throughout. the coils. By maintaining this constant temperature a constant reaction is obtained throughout the coil resulting in a better control and a higher yield than if the temperature were allowed to fluctuate over any substantially wide limi s. By splitting the coils between two furnaces a more exact control of the heating of the several coils is obtained, and also a support for the supporting beams which are required is obtained.

The above is not to be taken as limiting our invention, but merely as illustrative of the best manner of carrying out our invention, which we claim to be:

1. The process of cracking oil, comprising. passing the oil through connected coils in the hottest zone of a furnace in a flow generally concurrent with the flow of combustion gases of the furnace to quickly heat the oil to a cracking temperature then passing the oil into coils which direct it alternately concurrent then counter-current through hotter to cooler zones of the furnace and vice versa and maintaining these alternate directions of flow through a series of changes from concurrent to counter-current directions of flow to maintain the oil at a substantially constant temperature after it is heated.

2. A process of cracking oil, comprising, passing oil under pressure through connected pipe coils situated in the hottest section of a double furnace, alternately from one section of the furnace to another section of the furnace and in a general flow concurrent with the flow of combustion gases, and heating the oil to a cracking temperature, then passing the oil under pressure and at cracking temperature through connected pipe coils situated above the first mentioned pipe coils, concurrent with the flow of combustion gases from a hotter zone into a cooler zone of the furnace, then countercurrent with the flow of combustion gases from the cooler zone into the hotter zone of the furnace, and maintaining these alternate directions of flow through the pipe coils situated above the first mentioned pipe coils from concurrent to countercnrrent directions of flow to maintain the oil at a substantially constant cracking temperature by alternately supplying the heat rendered latent by the cracking reaction.

3. A process of cracking oil, comprising, passing oil under pressure through pipe coils situated in the hottest section of a double furnace and heating the oil to an active cracking temperature, then passing the oil at said pres sure and at said cracking temperature through pipe coils situated above the first mentioned pipe coils, concurrent with the flow of combustion gases from a hotter lower zone into a cooler upper zone of the double furnace, then countercurrent with the flow of combustion gases from the upper cooler zone into the hotter lower zone of the furnace, and maintaining these alternate directions of flow through the pipe coils situated above the first mentioned pipe coils from concurrent to countercurrent directions of flow to maintain the oil at a substantially constant cracking temperature.

i. A process of cracking oil, comprising, continuously passing oil in a regulated stream flow under pressure through pipe coils situated in the hottest section of adouble furnace heated by furnace gases, and heating the oil to a cracking temperature, then passing the oil under pressure and at said cracking temperature in a continuous regulated stream flow through pipe coils situated above the its first mentioned pipe coils, concurrent with the flow of combustion gases from the hotter zone into the cooler zone of the furnace, then countercurrent with the flow of combustion gases from the cooler zone into the hot-tor Zone of the furnace, and maintaining these alternate directions of flow through a series of changes from concurrent to countercurrent directions of flow to maintain the oil at a substantially constant cracking temperature by alternately supplying the endothermic heat of the cracking .reaction.

5. A process of cracking oil, comprising, passing oil under pressure through a pipe coil situated in a furnace and heating the oil to a cracking temperature, then passing the oil into a second coil situated above the first mentioned coil in a cooler section of the furnace, continuously passing the oil through the second coil alternately concurrent and countercurrent with the flow of combustion gases from hotter and lower section to an upper and cooler section of the second coil, and from the upper and cooler section to the lower and hotter section of the second coil, and maintaining these alternate directions of flow through the second pipe coil from eoncurrent to countercurrent directions of flow to maintain the oil at a substantially constant cracking temperature by alternately supplying the heat rendered latent by the cracking reaction.

6. A process of cracking oil, comprising, passing oil under pressure through a pipe coil situated in a double furnace and heating the oil to a cracking temperature, then pas ing the oil into a second coil situated above the first coil in a cooler section of the double furnace, continuously passing the oil alter nately concurrent and countercurrent with the flow of combustion gases from a hotter and lower section to an upper and cooler section of the second coil. and from the upper and cooler section to the lower and hotter section of the second coil, and maintaining these alternate directions of flow through the second coil from concurrent to countercurrent directions of flow to maintain the oil at a substantially constant cracking temperature.

7. A process of cracking oil, comprising, beating an oil in a continuous stream flow under pressure to a cracking temperature in a primary set of coils situated in a double furnace, continuously passing the oil from the primary set of coils into a secondary set of coils situated above the primary set of coils, continuously passing the oil through the secondary set of coils alternately concurrent and countercurrent with the flow of combustion gases from a lower and hotter section to an upper and cooler section of the secondary set of coils, and from the cooler and upper section to the lower and hotter section of the secondary set of coils, and maintainingthese alternate directions of How through the secondary set of coils from concurrent to countercurrent directions of flou to maintain the oil at a substantially constant cracking temperature by alternately supplying the heat rendered latent by the cracking reaction.

8. A process of cracking oil, comprising, passing oil under pressure through connected pipe coils situated in the hottest section of a double furnace. alternately from one furnace to the other and in a general flow concurrent with the flow of combustion gases to heat the oil to a cracking temperature, then passing the oil under pressure and at cracking tempcrature through a series of vertically connected pipe coils so disposed that the flow of oil passes alternately concurrent then countercurrent with the flow of combustion gases throughout the series of coils, whereby a substantially uniform cracking temperature is maintained in said series of coils.

In testimony whereof We affix our signatures.

JOHN C. BLACK. EARLE W. GARD. 

